Apparatus for the removal of non-metallic impurities from molten metal

ABSTRACT

Apparatus for use in connection with a permanent mold includes a refractory body having a passage connected to the ingate of the mold. Metal is poured through the passage in order to remove nonmetallic impurities therein. Various types of such devices are described in connection with a bottom pressure casting system.

United States Patent Troy et al.

APPARATUS FOR THE REMOVAL OF NON-METALLIC IMPURITIES FROM MOLTEN METAL Inventors: Walter C. Troy, Evanston, IlL;

James J. Novak, Miami, Fla; Richard C. Costello, West Chicago; Raymond J. Dearth, Roselle, both of III.

Amsted Industries Incorporated, Chicago, Ill.

Filed: Mar. 14, 1969 Appl. No.: 807,192

Assignee:

[1.8. CI. [64/306; 164/134; 164/337 Int. Cl 822d 17/06 Field of Search 164/113, 119, 133, 134,

[451 July 1, 1975 [56] References Cited UNITED STATES PATENTS 3,032,84l 5/l962 Sylvester 164]! 19 3,196,503 7/[965 Sylvester l64/306 X FOREIGN PATENTS OR APPLICATIONS 242,365 I2/l962 Australia 164/309 Primary Examinerl. Spencer Overholser Assistant Examiner.lohn E. Roethel 5 7 1 ABSTRACT Apparatus for use in connection with a permanent mold includes a refractory body having a passage connected to the ingate of the mold. Metal is poured through the passage in order to remove non-metallic impurities therein. Various types of such devices are described in connection with a bottom pressure casting system.

2 Claims, 10 Drawing Figures PATENTFHJUL 1 SHEET FIG. 6

FIG.

FIG. 8

FIG. 7

III! III/II FIG. IO

APPARATUS FOR THE REMOVAL OF NON-METALLIC IMPURITIES FROM MOLTEN METAL This invention relates to the removal of non-metallic impurities from molten metal and more particularly to the prevention of non-metallic related defects in products made by casting molten metal in permanent molds by bottom pressure casting.

Non-metallic impurities. such as slag. ceroxides and ladle refractories in molten metal. are undesirable to the extent that such impurities may cause voids and other defects in castings made from the metal. In the conventional gravity pouring of sand molds. a horizontal runner system is usually included in the sand body of the mold to convey molten metal from the pouring sprue to the gate of the casting cavity. Since the mold body is composed of sand or other materials that are isomorphic with the objectionable non-metallic impurities in the molten metal, such impurities. because of their relatively light weight. tend to rise and adhere to the upper surface of the runner during passage of the metal therethrough. thereby cleaning the metal prior to its entrance into the casting cavity. Sand molders usually construct such runners longer than the minimum length required for the function of distributing the metal. in order to achieve a greater degree of cleanliness in the metal reaching the casting cavity.

The runner system. however. is not feasible in the casting of molten metals. such as steel. in permanent or semi-permanent molds composed of such materials as graphite. cast iron. steel or copper. Since temperature loss is more rapid in such molds. the use of long runners would result in premature freezing of the metal or would cause the casting to be bound within the mold. Moreover. the permanent mold materials mentioned above do not physio-chemically attract non-metallic impurities under normal casting conditions.

Permanent molds are commonly used in connection with bottom pressure casting wherein pneumatic pressure is used to force the molten metal upward through a pouring tube directly into the casting cavity of the mold. Heretofore, it has not been considered feasible to apply the runner technique to the bottom pressure casting process because of the considerations mentioned above.

Accordingly. an object of this invention is to provide a method and apparatus for removing non-metallic impurities from molten metal in a permanent molding process.

Another object is to incorporate the advantages of a sand runner system into a permanent molding process.

A further object is to provide a method and apparatus for the removal. by physio-chemical attraction. of non-metallic impurities from molten metal in a bottom casting operation using permanent molds.

Other objects will appear in the following description and claims. taken in connection with the accompanying drawings. wherein:

FIG. I is a simplified elevational view, partly in cross section. of a bottom casting apparatus that incorporates features of the presently described invention;

FIG. 2 is a simplified perspective view of an apparatus similar to that shown in FIG. 1. which may be used to simultaneously fill a plurality of molds;

FIG. 3 is a vertical cross sectional view of another embodiment of the present invention;

FIG. 4 is a transverse sectional view of the embodiment shown in FIG. 3;

FIG. 5 is a vertical cross sectional view of a further embodiment of the present invention;

FIG. 6 is a horizontal cross sectional view of the embodiment shown in FIG. 5;

FIG. 7 is a schematic view of a still further embodiment of the present invention;

FIG. 8 is a side schematic view of an even further embodiment of the present invention;

FIG. 9 is a plan schematic view of the embodiment shown in FIG. 8; and

FIG. 10 is a plan schematic view of another embodi ment similar to that shown in FIG. 8.

Referring in greater detail to the drawings. FIG. l H lustrates a bottom pressure casting system comprising a ladle 10 containing molten metal 12 disposed in an air tight tank 14 having a removable cover [6 sealed thereon. A refractory pouring tube 18 extends from the interior of the ladle 10 through the cover 16 in a sealed relationship and terminates in a flanged adapter 20 for receiving one end of a slag control device. generally indicated at 22. A flanged adapter 24 is provided at the other end of the slag control device 22 to receive the ingate portion 26 of a permanent mold 28 having a casting cavity 30 therein in communication with the bore 32 of the ingate.

The slag control device. generally indicated at 22, is composed of a refractory material such as sand or clay and is so constructed to form a relatively long and substantially horizontal passage 34 sloping slightly upward from the end of the device connected to the pouring tube [8 to that portion connected to the ingate 26 of the mold 28. A blind extension 36 of the passage 34 is provided beyond the upper adapter 24 of the device. in order to collect the initial contaminated metal during that time in which the device is being filled.

In operation. pneumatic pressure is applied to the tank 14 from a suitable supply 38, causing molten metal 12 to rise upward in the pouring tube and to be diverted from vertical flow during passage through the slag device 22 and into the casting cavity 30 of the mold 28. Laminar flow of the molten metal through the length of the passage 34 allows nonmetallic impurities to rise and adhere to the isomorphic upper surface of said passage. thereby cleaning the metal prior to its entry into the casting cavity 30. The initial charge of metal containing relatively high amounts of impurities is collected in the blind extension 36.

FIG. 2 shows a similar slag control device that permits simultaneous filling of a plurality of molds. A common supply branch 40 having an adapter 42 for the pouring tube communicates with at least two secondary branches 44 and 46 through a common tee member 48. A plurality of outlets 50 may be provided on each secondary branch 44 and 46 in communication with a permanent mold. As before. the impurity control device is composed of a refractory material that is isomorphic with the impurities in the molten metal.

FIGS. 3 and 4 illustrate another embodiment of the impurity control device comprising horizontal top 52 and bottom 54 walls interconnected by spaced vertical side walls 56 and end walls 58 and 59 to define a chamber 60 therein. which is lined with refractory tile 62 or other refractory material. A molten metal inlet 64 is provided at one end of the chamber 60 through the bottom wall 54, and an outlet 66 to the mold (not shown) is provided in the top wall 52 of the device in vertical alignment with the inlet. A transverse horizontal weir 68 is secured between the side walls 56 and at the end wall 58 proximate the inlet 64 and outlet 66, with the end thereof that is remote from said inlet being spaced from the other end wall 59. Blind extensions 70 and 72 may be provided respectively above and below the horizontal weir 68 adjacent the outlet and inlet passages 66 and 64. respectively. to entrap excess non-metallics.

It may be seen that metal entering the inlet 64 follows the path indicated by the arrows 74 out and around the remote end ofthe weir 68 and back and up through the outlet 66, during which time the non-metallic impurities rise and adhere to the walls of the chamber 60.

FIGS. and 6 show an embodiment similar to that shown in FIGS. 4 and 5, except the chamber for molten metal travel is in the form of a loop. The device comprises a solid refractory body 76 having an inlet 78 at one side thereof connected by a right angle elbow 80 to a first loop 82 preferably constructed from refractory tubing. The end of the first loop 82 is connected by a sleeve 84 to a return loop 86, which terminates in a right angle elbow 88 above the inlet elbow 80 and communicates with the outlet 90. which is preferably coaxial with the inlet 78. It may be seen in FIG. 5 that both loop sections 82 and 86 are arranged to slope slightly upward.

FIG. 7 schematically illustrates another embodiment wherein the lower inlet 92 and the upper outlet 94 are at opposite ends of the device. and a weir 96 depends downward from the upper surface of the device. which serves to trap impurities on the inlet side.

FIGS. 8 and 9 schematically illustrate a centripetal device comprising a vertical cylindrical shaped chamber 98. As best seen in FIG. 9, the inlet 100 enters the lower part of the cylindrical chamber 98 on a tangent. in order to impart a circular or swirling motion to the metal. The outlet 102 is located near the top of the chamber 98 on a tangent in the same direction as the direction of metal flow, Sufficient spaced is provided in the chamber 98 above the outlet 102 to entrap accu mulating nonmetallic impurities, and a horizontal blind extension 104 is provided to catch the initial contaminated molten metal as the chamber 98 is being completely filled. The direction of flow of the molten metal is illustrated by the arrows, and it may be seen that a swirling motion is imparted to metal passing through the chamber. The centripetal force on the relatively light non-rnetallic particles causes accumulation thereof in the center of the top wall of the chamber,

LII

where they may adhere to said wall.

FIG. 10 shows a modification of the device shown in FIGS. 8 and 9. In this instance. the outlet 102' is located on a tangent opposite to the circular flow of the molten metal imparted by the inlet From the description of the foregoing embodiments. it may be seen that the impurity control device is constructed such that the metal flow therethrough is diverted from its normal path of flow, in order to allow sufficient time to allow non-metallic impurities to adhere to the body of the device. Since the impurities tend to rise in a generally vertical direction. it is necessary to divert the flow away from vertical by constructing the passage to be horizontal or angular. thereby allowing the non-metallic impurities to adhere to the upper surface of the passage.

Having thus described the invention, what is claimed 1. In a bottom pressure casting arrangement including means for forcing molten metal vertically upward from a ladle through a pouring tube and into the casting cavity of a mold by the application of super atmospheric pressure to said metal, apparatus for removal of non-metallic impurities from said molten metal comprising a body disposed between said pouring tube and said mold. said body composed of a refractory material that is isomorphic with at least a portion of said impurities, a passage through said body, an outlet from said passage in communication with said casting cavity, an inlet into said passage communicating with said pouring tube. said passage being substantially horizontal and constructed to divert metal flow there through away from vertical flow to allow relatively light impurities in said molten metal to rise therein and adhere to said body. and a substantially horizontal weir in said body dividing said passage into an upper passage and a lower passage, said inlet communicating with said lower passage proximate one end thereof, said outlet communicating with said upper passage proximate the same end thereof as said inlet, and said weir being spaced from said body at the other end of said upper and lower passages to provide a vertical passage between said upper and said lower passages.

2. The invention according to claim 1 wherein said inlet and outlet are substantially vertically aligned, said outlet being spaced from the end of the upper passage most closely adjacent thereto to provide a blind end extension thereof for receiving the initial charge of molten metal. 

1. In a bottom pressure casting arrangement including means for forcing molten metal vertically upward from a ladle through a pouring tube and into the casting cavity of a mold by the application of super atmospheric pressure to said metal, apparatus for removal of non-metallic impurities from said molten metal comprising a body disposed between said pouring tube and said mold, said body composed of a refractory material that is isomorphic with at least a portion of said impurities, a passage through said body, an outlet from said passage in communication with said casting cavity, an inlet into said passage communicating with said pouring tube, said passage being substantially horizontal and constructed to divert metal flow there through away from vertical flow to allow relatively light impurities in said molten metal to rise Therein and adhere to said body, and a substantially horizontal weir in said body dividing said passage into an upper passage and a lower passage, said inlet communicating with said lower passage proximate one end thereof, said outlet communicating with said upper passage proximate the same end thereof as said inlet, and said weir being spaced from said body at the other end of said upper and lower passages to provide a vertical passage between said upper and said lower passages.
 2. The invention according to claim 1 wherein said inlet and outlet are substantially vertically aligned, said outlet being spaced from the end of the upper passage most closely adjacent thereto to provide a blind end extension thereof for receiving the initial charge of molten metal. 